Rotary wing aircraft



Jan. 3, 1950 E. A. STALKER ROTARY WING AIRCRAFT 2 Sheets-Sheet 1 Filed Sept. '7, 1944 o /0 /0 IO IO F/& J

Jan. 3, 1950 E. A. STALKER 2,493,041

ROTARY WING AIRCRAFT Filed Sept. 7, 1944 2 Sheets-Sheet 2 I .268 w 66 .59 INVENT R.-

FIG. 8

Patented Jan. 3, 1950.

uulfrsp I STATES PATENT OFFICE ROTARY WING AIRCRAFT Edward A. Stalker, Bay City, Mich. Application September 7, 1944, Serial No. 553,682

10 Claims. I'm-135.4)

charged on the advancing side of the orbit than on the retreating side when in horizontal flight.

Another object is to provide a means of changing from the condition of uneven discharge about the orbit to uniform discharge for hovering flight.

Still another object is to-provide a cam means which prescribes a pattern of action for changes of blade pitch superimposed on another pattern of action resulting from a first cam means. Other objects will appear from the specification and drawings. 1 g

I accomplish the above objects by the means illustrated in the accompanying drawings in which-,

Figure 1 is a side elevation of a helicopter;

Figure 2 is a'fragmentary top plan of a blade;

Figure 3 is a section along the line 3-3 in Figure 2;

Figure 4 is a fragmentary plan of the mechanism to operate the auxiliary flap;

Figure 5 is a fragmentary elevation of the hub part of the mechanism of Figure 4 on line 5--l of Fig. 4;

Figure 6 is a fragmentary vertical section 8-6 of Figure 2 showing the manner in which the blad root forks are fastened to the hub;

Figure 7 is a top fragmentary view of the rotor hub and part of the flap actuating mechanism;

Figure 8 is a side view of the elements of Figure 7; and

Figure 9 is a top fragmentary view of the wing, flap and actuating mechanism in the region 9-! of Figure 2.

/ 2 be largest for the retreating blade so as to support it. This will be shown to be undesirable for the aircraft herein described. If the blade is equipped witha slot in its upper surface it is possible to support the retreating blade by increasing its lift by a jet out the slot. Especially if the jet effect is combined in a special manner with a flap the quantity and/or the speed of the jet can be greatly reduced. It is in" fact desirable to reduce the energy of the jet to a minimum because when the type of flap to be described is depressed the jet is directed downward rather than rearward. Hence a large part of the propulsive effect of the jet is lost. It is therefore desirable to reduce the energy of the jet of the retreating blade to the amount just necessary to obtain the increase in lift coeflicient in conjunction with the flap and to increase the total energy of the jet out of the advancing blade to provide the main propulsive When a helicopter is hovering or climbing vertically in still air the magnitude of the velocity blade than past the advancing blade. If the jet is reliedupon to change the lift coefllcients of the blades there should be a dissymmetry in the jets as regards volume and speed. i It has always been force to rotate the lifting rotor and propel the aircraft forward. y

In forward flight the retreating blade is subjected to a reduction in relative wind speed and hence it is possible to reduce the volume of the jet as compared to the advancing blade. The required energy of the jet for lift augmentation by boundary layer control is proportional to the energy of the relative wind. On the retreating blade the relative wind velocity is low, requiring therefore only a small jet energy.

In order that the advancing blade does not generate too much lift (and be forced against the limit stops in vertical flapping) the blade flap must be raised on the advancing blade.

The mode of operation of the rotor blade consists in lowering the flap on the reatreating blade and restricting the flow out of the jet while raising the flap on the advancing blade and enlarging the flow out of its slot to propel the blades.

In vertical flight the blade flaps are to be depressed not at all or preferably only slightly so assumed previously that the jet lift eflect should that the jets exert substantially their full eflect in propelling the blades. One of the devices described herein is a means for cyclically varying the amount of. air blown from the slot of a jet driven helicopter rotor blade while the machine is in forward flight, and for providing a uniform air flow from the blade when the machine is hovering. The cyclic change inairflow is from a high to a low quantity of discharge. The uniform air flow discharges at an intermediate rate.

The change in amount of airflow is accomplished by varying the width of the slot exit through the agency of a small rotatable flap which forms one side of the slot. The cyclic change is such that a large amount of air is discharged through the widened slot while the rotor blade is on the advancing side of its orbit, and a small amount of air is discharged through the nafiowed slot on the retreating side of the blades or 1 The helicopter of Figure 1 has the rotor blade I supported from the hub 2 and free to flap vertically about the axis 2a. The blade is equipped with the main flap 3 and the auxiliary flap 4. Each blade is attached by the fork la to the hub to be revolved-about a vertical axis. As shown in Figure 3 the main flap has an upper contour of radius R so that rotation of the main flap about the hinge at the origin of the radius does not vary the slot between the auxiliary flap 4 and flap 3.

The rotor is revolved by a jet of air emitted from the passage 5 through the slot 8 rearward along the surface of the flap. This type of pro- Since the advancing blade has a velocity Va equal to the sum of the rotational and translational speed, the sum can more nearly approach the jet velocity V 1 From another point of view it may be observed that the-jet from the advancing blade both rotates the rotorand propels the helicopter forward.

The emission of the jet mainly from the advancing blade greatly increases the efliciency of propulsion of the whole machine.

The auxiliary flap 4 which is hinged at 8 is raised on the advancing blade to increase the opening of the slot and it is lowered on the retreatingsideto decrease the slot opening. The slot width should be varied rapidly when the blade is near the front and back positions. This is accomplished by the variable displacement means incorporating the cam plate Ill whose cam groove 3 accommodates the end of arm I attached to the flap 4. The cam plate is slideable on the rollers i l and when such motion takes plates the arm I is moved to rotate the auxiliary flap.

The motion of the cam plate It! is referred to the orbital position of the blade about the upright axis by means of the cam l2 and suitable mechanism connecting it to the cam plate.

Cam I 2 is attached rigidly to shaft I 3 which is in turn fixed ri idly to the aircraft structure. Plate l4 is part of the hub to which the helicopter. blades i are attached and is free to rotate on bearings I 5.- Fork l6 which is part of plate l4 supports fork I! on the axis l8. Fork I1 is an integral part of arm is which is caused to oscillate around axis I! by roller riding in the slot of cam l2. Fork 2| is pinned to nut block 22 at one end and at the other to slide rod 22a which slides in sleeve 22!: su ported on arm 22c which is part of late N. Slide rod 22a actuatesflexible push-pull or Bowden cable 23 which transmits spandwise motion to slide rod 23a and in turn moves cam plate ll. Slide rod 23a is supported by sleeve 24 which is fastened to the blade structure. The blade I is free to swing vertically around horizontal hinge 2a which causes sleeve 24 and slide rod 23a to move up and down relative to slide rod 22a. Flexible Bowden cable 23 permits this relative vertical motion without affecting the spanwise positions of either slide rod 22a or 23a. blade structure, allow cam ill to slide spanwise. Link 25 connects a plurality of cams identical to ill distributed along the span. Nut block 22 can be moved so that axis 26 can be moved from position A to position B by revolving screw 21. Screw 21 is turned by pinion 28 mating with rack 29. Universal joint 30 fastened to rack 29 lies on axis l8 so that oscillation of arm I3 will not affect the vertical position of rack 29. Link 3! is moved by arm 32 which is pivotally supported by fork 33. They revolve with hub l4 around shaft l3. Grooved sleeve 34 does not revolve on shaft l3 but is freeto slide vertically by the action of bellcrank 35 and link 36. The last is attached to a control operable by the pilot.

For forward flight, nut block 22 remains fixed at the outer end of crank I 8 and oscillates between positions A and C by the action of roller 20 in cam l2. Cam In is thereby caused to reciprocate moving roller 3 and arm 1 causing flap 4 to move from position D to F and back.

As the rotor blade revolves around its orbit from G to H (see Fig. 4 of which direction GK 1s forward) the flap 4 opens from F' to D (see Fig. 3). As the blade revolves from H to I to J the flap 4 remains wide open. Revolving from J to K the flap 4 closes down again to F and remains there while the blade revolves to L and then to G.

In hovering flight nut block 22 is moved from position A to B with the screw 21. Position B is on axis l8, therefore the oscillation of crank arm I9 imparts no motion to link 2|. The geometry of point B relative to A and C is such that cam ill is held at an intermediate position putting flap 4 into fixed position E.

A like type of mechanism is used to control the angular position of flap 3 as for flap 4.

The ring 60 is tiltable universally and for a given attitude of tilt determines a displacement about its perimeter of roller 32 which is sinusoidal. The displacements on opposite sides of the axis of rotation are opposite but of equal magnitude. This means that with direct connection to the flap that it would be moved through equal angles. This will not be desirable for substantial advance ratios. This may be.noted from the fact that as the forward speed increases less of the retreating blade is lifting while all of the advancing blade continues to lift. Hence it is desirable to have a different variation of flap displacement around the orbit than provided by the I sinusoidal function of the ring 60. A mechanism to give a different variation will now be disclosed.

A suitable linkage enables the pilot to tilt control ring 60 which imposes a cyclic motion on blade flap 3. The motion is such that flap 3 is up to position D' (Fig. 3) on the advancing side of its orbit and down to position F on the retreating side of its orbit.

The relationship of positions between flap 3 and slot flap 4 during forward flight is that on the advancing part of the blades orbit, flap 3 is up to D reducing the lift coeflicient while slot flap 4 is wide open to position D permitting a large volume of air discharge contributing direct thrust to the aircraft as well as creating torque on the blades. The lift coeflicient is reduced because of the high relative speed of the advancing Rollers ll, supported by the v 8' blade. On the retreating side of the blades orbit, flap 8 is down to position F and slot flap 4 is down to position F discharging only enough air to create a high lift coemcient. For hovering and climb conditions flap-3 remains at or near position E and slot flap 4 remains at position E throughout the blade's orbit.

Ring 60 is mounted on spherical sleeve 84 with balls enabling it to be tilted about any horizontal axis by rods 88 and 68 displaced 90'". to one with them but rides between flanges 'on ring 88 and is therefore forced up onone side of its orbit and down on the other depending on the amount of tilt given to ring 80. 4

As roller 82 moves up and down link It oscillates crank I2 which moves link [14 oscillating crank 18 and push-pull rod18; Rod 18' is con-' nected by universal joint 18 tosplined, shaft 80.

This shaft 80 carries the roller 82, See Figure 9.

Splined shaft 80 is prevented from revolving by splined sleeve 84 attached to the blade structure.

As roller 82 moves in and out, cylindrical cam 86 fastened to flap} is caused to revolve thereby moving the flap.

Tilting of control ring 88 displaces roller 62 up on one side and down an equal amount on the other. Crank 12 however is arranged to give differential motion to the succeeding linkage to roller 8.2. This differential motion added to the.

differential action of cam 86 causes the flap 3 to revolve down on the retreating part of its orbit a great deal more below position E than it revolves above position E on the advancing side of its orbit. The ilap'8 reaches position E when the blades orbital position is ahead and behind the upright axis of rotation in forward flight.

Uniform control of the blades regardless of their orbital positions (necessary for hovering and climbing) is accomplished by'vertical sliding of sleeve 84 by rod 88 which elevates ring 68 without tilting it thereby giving uniform motion to the flap actuating linkages. I Sleeve 64 slides on cylinder 88 which is an integral part of hub It.

A depression of flap downward is equivalent to a change in pitch of the blade. It is in fact a change in the effective pitch of the flap portion of the wings.

A movement of the flap 4 causes both a change in propulsive eflort and a change in lift of the blade.

The width of the plan form of the blade increases to the inner end of the flap to provide a low velocity at the locality where the flap would tend to restrict the flow. In other,words since the flap does not conduct flow within the blade, its presence deletes part of the duct cross section.

I have now described suitable embodiments of my invention which are now preferred. It is to be understood however that the invention is not limited to the particular construction illustrated and described and that I intend to claim it broadly as indicated by the scope of the appended claims.

I claim:

1. In combination in a helicopter, a blade rotatable about an upright axis, variable thrust producing means on said blade, means for varying the lift of said blade, and control means for controlling the force exerted on said blade by said thrust producing means and for controlling the action of said lift varyingmeans to vary said force and said lift cyclically and inversely during blade rotation.

another. As the blades rotate,.roller 82,.revolves- I 2. In combination in a helicopter, a blade rov tatable about an upright axis, means to. vary the lift of said blade. jet thrust producing means for said blade including a variable discharge slot in said blade forming means to vary the; force of said jet, and cyclically operative control means for decreasing the lift of said blade and increasing the force of said jetin the advancing posi- 'tion of rotation .of the blade. 3. In combination in a helicopter, a blade rotatable about an upright axis, means to vary the lift, of saidblade, jet thrust producing means for said blade including a variable dischargeslot in ing the force of said jet in the advancing position corporating means ;for effecting a rapid ,change 20 in the force of said discharge jet when said blade nears its front and back positions.

4. In combination ,in a helicopter, a blade rotatable about an upright axis, means to'vary the lift of said blade, jet thrust producing means for said blade including a variable discharge slot in said lade, adjustable control means operable cyclically for decreasing the lift of said blade and increasing the force of said discharge jet in "the advancing position of said blade during forward flight, and means for adjusting said control means to maintain a substantially uniform force ofsaid discharge jet during vertical flight.

' .5. In combination in a direct lift aircraft, an adjustable pitch blade supported for rotation about an upright axis, thrust producing means for said blade including a spanwise passage therewithin, means forming a slot in the upper surface of the blade leading out of said passage adapted to discharge a fluid jet, the walls of said slot being -1 formed to direct the jet fluid toward the blade trailing edge substantially along the blade surface, means to control the volume of said jet to vary the thrust produced thereby, means to increase the effective pitch of said blade while in the retreating position and decrease the effective pitch while in the advancing position of rotation, and means for actuating said volume control means to increase the jet flow in advancing positions of blade rotation over the let flow in retreating positions of blade rotation.

6. In combination in an aircraft, a hollow [blade rotatable about an upright axis, thrust producing means for said blade including a slot in the surface thereof leading into the blade interior and adapted to discharge a propulsive jet to rotate said blade about said axis, said blade having a flap, means for adjusting said flap to increase the lift when the blade is in a retreating position and to decrease the lift when the blade is in an advancing position, means for varying the discharge opening of said slotto control said propulsive jet, and means to control SPld slot varying means to discharge the greater jet volume through the slot of the blade in the advancing position of rotation.

7. In combination, a fuselage, a blade supported on the fuselage for rotation about an upright axis, said blade having an adjustable flap rotatable relative to the blade main body about a spanwise axis from a normal position substantially in trailing alignment with said main body, thrust producing'means for said blade including a discharge slot in theupper surface thereof leading out of the blade interior to discharge a fluid jet to rotate the blade about of rotation of the blade, said control means inthrough said slot, means to rotate said iiap downward on the retreating blade to agreater degree than the flap is rotated upward on the advancing blade from said normal position, and means actuating said flow control means for decreasing the volume of now through the slot of the blade in the retreating position of rotation thereof relative to the volume of flow through the slot of the blade in the advancing position of rotation thereof.

8. In combination in a helicopter, a hollow wing rotatable about an upright axis, said wing having a slot in its surface leading out of the wing interior, means for discharging through said slot a Jet flow to propel the wingabout said axis, means to control the now through said slot, said wing having a flap, means to rotate the flap downward to increase the wing lift, and means actuating said flow control means coincidentally with said flap means rotating said flap to wing lift increasing positions to decrease the volume of flow through said slot.

9. In combination in an aircraft, a blade main body, an adjustable main flap supported at the rear of said body to form a blade and leaving an opening therebetween into said blade interior, means supporting said blade for rotation about an upright axis, a flow control flap, means for adjustably supporting said flow control flap at its front edge on said main body to extend in overlying relation with respect to said main flap and said opening, the rear edge of said control flap being normally spaced from the surface of said main flap to form a slot having communication with said blade interior through said opening, means to displace said main flap downward while maintaining a press-signed width of said slot, means operable independently of said displacing means to adjust the position of said control flap to alter the width of said slot, and

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means to cause a flow of iiuid through said slot.

101m combination in a helicopter, a blade .main body, an adjustable main flap supported at the rear of said body to form a blade and leaving an opening therebetween into said blade interior, a flow control flap, means for adjustaa bly supporting said flow control nap near its front on said main body to'extend in overlying relation with respect-to said main flap and said opening, means supporting said blade for rotation about an upright axis, the rear edge of said control nap being normally spaced from the surface of said flap to form a slot in communication with said blade interior through said openins, means to rotate said main nap downward, the upper surface of said main iiap being formed with a radius of curvature so that said upper surface has a substantially constant distance from the rear edge of said control flap during rotation of said main flap to provide a substantially constant slot width, means-to adjust the position of said control iiap to vary said slot width, and means to cause a flow of air through said slot;

EDWARD A. STALKER.

REFERENCES CITED UNITED STATES PATENTS M00 Jan. 8, 1936 

